Conservative party members want David Cameron to bring back the former chancellor Kenneth Clarke and the ex-shadow home secretary David Davis in his next frontbench reshuffle, according to a poll published yesterday.

The release of the survey, which also shows that a significant minority of Tories want George Osborne to be replaced as shadow chancellor, coincided with speculation that Cameron could give Clarke the business portfolio, putting him up against Lord Mandelson.

Gordon Brown's surprise decision to recall Mandelson to the cabinet has been seen as a success and, in Tory circles, it appears to have strengthened the feeling that Cameron could also benefit from the return of a veteran "big beast".

A party spokeswoman refused to comment on Cameron's reshuffle plans, although one shadow minister said he thought "a Clarke comeback in some form is quite likely to happen."

The poll, which was carried out by the ConservativeHome website over Christmas and involved 1,816 party members, showed that 50% of them would like Clarke back in the shadow cabinet, while 41% said they were opposed to the idea.

There was far more support for a Davis comeback, with 72% of respondents in favour and only 22% opposed. Worryingly for Osborne, only 55% said they wanted to see him stay as shadow chancellor, while 31% said he should be moved.

Tory MPs have been expecting a reshuffle for months. Cameron made only minor changes to his frontbench line-up after Brown's autumn reshuffle and, with the Tory lead in some polls slipping in the run-up to Christmas, a more extensive shake-up is thought to be overdue, although yesterday party sources dismissed rumours that it could come as early as next week.

Although there is more grassroots support for Davis, some Tories believe that Clarke - whose pro-Europeanism contributed to him losing in three leadership contests - is more likely to make it into the shadow cabinet.

Three years ago Cameron offered Clarke the post of shadow leader of the Commons. Clarke turned it down because it was "tedious being an opposition spokesman" and only this weekend, in an interview in the Observer, he said that being a backbencher was "a great freedom". But Clarke has also spoken about how he misses being in government and, with the Tories ahead in the polls, an election due within 18 months and the recession set to dominate the political agenda in 2009, some Tories believe he could be tempted to accept the business portfolio.

In media terms this would pit Clarke, an accomplished television performer, against Mandelson. But they would not face each other at the dispatch box because Mandelson is in the Lords. Alan Duncan, the current shadow business secretary, is thought by some colleagues to be "a bit erratic" and has been tipped for demotion.

Osborne enjoys Cameron's full support and seems almost certain to stay in his post. But it is less clear what will happen to Davis, who resigned from the shadow cabinet - against Cameron's wishes - to fight a byelection over his opposition to Labour's plans for 42-day pre-charge detention. Davis is ambivalent about returning to the frontbench and, although Cameron is thought to be considering offering him a job, it is thought he is nervous about the possible consequences.

"There would be a lot of risks involved," said one Tory frontbencher. "What happens if he walks out again?"

Separately, William Hague, the shadow foreign secretary, defended the right of frontbenchers to top up their parliamentary salaries with paid work outside politics. Cameron floated the idea of banning frontbenchers from such "moonlighting" but backed down after being warned about the scale of opposition to the plan.

Hague, who earns at least £230,000 from directorships and after-dinner speaking, told BBC Radio 4's World at One: "I take what you might regard as an old-fashioned view ... that actually you can gain in your effectiveness as a politician from a wide acquaintance with the world and from a degree of independence that having some outside interests gives.

"Some people want politics to be totally professionalised ... I have written books on history, on Pitt and Wilberforce. I think it is a net gain to politics for some of us to have interests of that kind and I think it has been a net gain to British politics over a very long period for politicians to have some of these sorts of interests."

Grandees at a glance

Kenneth Clarke, 68

Political Career Became MP for Rushcliffe in 1970. Served as a minister under Heath, Thatcher and Major, including spells as home secretary and chancellor. Backbencher since 1997

Successes Being chancellor at a time of rising prosperity

Failures Three Tory leadership bids

Enemies A large section of his party, partly due to his support for the euro